DE102015224437B4 - Vehicle electrical system voltage converter, vehicle on-board network with a vehicle electrical system voltage converter - Google Patents

Abstract

Vehicle electrical system voltage converter (SW) for converting a first vehicle electrical system voltage (U1) in a second vehicle electrical system voltage (U2) and a third vehicle electrical system voltage (U3), comprising: - a first power connection (A1) and a second power connection (A2) for connection to the first Vehicle electrical system voltage (U1), two primary winding circuits (WP1, WP2) connected in parallel between the first (A1) and second (A2) power connections, - a third power connection (A3) and a fourth power connection (A4) for providing the second on-board voltage (U2), - two secondary winding circuits (WS1, WS2) connected in series between the third (A3) and fourth (A4) power connections, - a fifth power connection (A5) between the two secondary winding circuits (WS1, WS2) for providing the third vehicle electrical system voltage (U3) between the fifth (A5) and the fourth (A4) power connection, wherein in each case one of the two primary winding circuits a common smoothing inductor (LG) electrically connected between the two secondary winding circuits (WS1, WS2) and each one of the two secondary winding circuits (WS1, WS2) are electromagnetically coupled to each other; to reduce the second (U2) and the third (U3) vehicle electrical system voltage, - a controllable switch (ST), which is electrically connected between the smoothing reactor (LG) and the fifth electrical connection (A5) and is arranged, in an open switching state the fifth Disconnect the power connector (A5) electrically from the third power connector (A3).

Description

Technical area:

The invention relates to a vehicle electrical system voltage converter and a vehicle electrical system with a said vehicle electrical system voltage converter.

State of the art:

Multi-voltage electrical systems of motor vehicles, in particular hybrid electric / electric vehicles, with several electrical system branches have at least one vehicle electrical system voltage converter, which is configured to convert a vehicle electrical system voltage of a vehicle electrical system branch into another vehicle electrical system voltage of another electrical system branch and / or vice versa.

In particular, there are three- or multi-voltage systems, in which three or more vehicle electrical system voltages are provided for different electrical components of the electrical system with different high operating voltages.

A publication US 2011/0 222 315 A1 describes a power distribution power device configured to stabilize voltage levels of an input DC voltage at a predetermined voltage level and apply the stabilized DC voltage to rear-end circuits. The power distribution power device includes a square wave generation circuit, a rectifier circuit, a conversion circuit, a rectifier circuit, a filter circuit, a first output terminal, and a second output terminal. The power distribution power device supplies two output voltages having a multiple relation to each other via the first output terminal and the second output terminal.

A publication DE 10 2009 028 973 A1 describes a DC / DC converter circuit having at least two DC / DC converters and a low-pass filter, wherein the DC / DC converters each have an input side and an output side and are connected to each other in series on their output side. The low-pass filter is connected downstream of the DC / DC converters and serves to smooth out an output voltage generated by the DC / DC converters on its output side.

A publication US 2004/0 037 092 A1 describes a circuit arrangement having a pair of conversion circuit parts formed in a full-bridge configuration.

A publication DE 10 2013 201 637 A1 describes a power transmission arrangement with an electromagnetic transducer unit which can be coupled on the input side with an AC voltage source, a first DC voltage circuit, which is coupled on the input side with the electromagnetic transducer unit and the output side with a first electrical DC voltage sink can be coupled. The DC voltage circuit is designed to provide a first DC voltage on the output side. The energy transmission arrangement further comprises a second DC voltage circuit which is coupled on the input side to the electromagnetic converter unit and on the output side can be coupled to a second electrical DC voltage sink. The second DC voltage circuit is designed to provide a second DC voltage on the output side, one of the DC voltage circuits having a DC voltage converter for setting its output-side DC voltage.

To convert these three or more on-board voltages thus requires a vehicle electrical system voltage converter, which is able to convert the three or more on-board voltages different voltage levels safely in each other on-board voltages.

Thus, the object of the present invention is to provide a way for safe and cost-effective conversion of the different electrical system voltages of a vehicle electrical system of a motor vehicle.

Description of the invention:

This object is solved by subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims.

According to a first aspect of the invention, a vehicle electrical system voltage converter for converting a first vehicle electrical system voltage in a second vehicle electrical system voltage and a third vehicle electrical system voltage to convert.

The vehicle electrical system voltage converter comprises a first power connection and a second power connection for connecting the vehicle electrical system to the first vehicle electrical system voltage and two primary winding circuits which are connected in parallel between the first and the second electrical connection.

The vehicle electrical system voltage converter further comprises a third power connection and a fourth power connection for providing the second vehicle electrical system voltage, as well as two secondary winding circuits connected between the third and the second the fourth power supply are connected to each other in series.

The vehicle electrical system voltage converter further comprises a fifth power connection between the two secondary winding circuits for providing the third vehicle electrical system voltage between the fifth and the fourth power connection.

In each case, one of the two primary winding circuits and one of the two secondary winding circuits are pairwise coupled to each other electromagnetically.

With the vehicle electrical system voltage converter described above, a voltage converter for a three- or multi-voltage vehicle electrical system with three or more mutually galvanically separate on-board network branches is created, which allows single-stage conversion of the first to the second and the third board electrical system voltage. The single-stage voltage conversion, compared to a multi-stage voltage conversion has a lower cost of components, a lower complexity of the circuit and thus low costs.

By the parallel connection of the two primary winding circuits and the series connection of the two secondary winding circuits, a high transformer gear ratio can be achieved, whereby the required dielectric strength of the electrical or electronic components used (taking into account the possible Abschaltüberspannungen) can be reduced. This in turn has the advantage that comparatively favorable electrical or electronic components can be used in the vehicle electrical system voltage converter. In addition, time-voltage surfaces may be used in inductive devices, e.g. be reduced to be described below primary and secondary windings. This in turn reduces costs in the vehicle electrical system voltage converter.

Preferably, the two primary winding circuits each comprise a full bridge circuit and a respective primary winding. In this case, the full bridge circuits each comprise two half bridges, wherein the primary windings of the respective primary winding circuits are electrically connected between the two half bridges of the corresponding full bridge circuits.

The two secondary winding circuits each comprise a secondary winding and a respective rectifier connected downstream of the respective secondary windings, the secondary windings being electromagnetically coupled to the respective primary windings of the corresponding primary winding circuits.

The vehicle electrical system voltage converter further comprises a common smoothing choke electrically connected between the two secondary winding circuits and configured to reduce AC components in the second and third vehicle electrical system voltages.

By sharing the smoothing choke and the staggered driving of the two primary winding circuits, the smoothing choke can be made smaller.

The vehicle electrical system voltage converter further includes a controllable switch electrically connected between the smoothing choke and the fifth power terminal and configured to electrically disconnect the fifth power terminal from the third power terminal in an open switching state.

Preferably, the second vehicle electrical system voltage is above 40 volts, in particular at 48 volts.

Preferably, the third vehicle electrical system voltage is below 40 volts, in particular at 12 volts.

The two primary winding circuits are preferably formed identical to one another in terms of circuitry.

Preferably, the two secondary winding circuits are also identical to one another in terms of circuitry.

The vehicle electrical system voltage converter further comprises a control unit for controlling the two primary winding circuits, which is further configured to control the two primary winding circuits or the full bridge circuits of the two primary winding circuits offset from each other by 90 degrees. In this case, the "offset activation" means that pulse-width-modulated control signals for controlling the semiconductor switches of the full-bridge circuits of the two primary winding circuits are offset by 90 ° relative to the signal period.

The control unit is preferably further configured, for providing the third vehicle electrical system voltage, to switch off the full bridge circuit of one of the two primary winding circuits and to operate the full bridge circuit of another of the two primary winding circuits in a half bridge operating mode. In this case, a half bridge operating mode is an operating mode in which a switch of one of the two half bridges of the full bridge circuit is switched off continuously and the other switch of the same half bridge is switched on continuously.

According to a further aspect of the invention, a vehicle electrical system, in particular for a hybrid electric / electric vehicle, is provided, which comprises a first on-board network branch with a first vehicle electrical system voltage, a second vehicle electrical system branch with a second vehicle electrical system voltage and a third vehicle electrical system branch with a third vehicle electrical system voltage.

The vehicle electrical system further comprises a vehicle electrical system voltage converter described above, via the first and the second power supply to the first electrical system branch, via the third and fourth power connection to the second electrical system branch, and electrically connected via the fifth and the fourth power connection to the third electrical system branch is and is set up to convert the first vehicle electrical system voltage of the first electrical system branch into the second vehicle electrical system voltage of the second vehicle electrical system branch and into the third vehicle electrical system voltage of the third vehicle electrical system branch.

Advantageous embodiments of the vehicle electrical system voltage converter described above, as far as possible transferable to the above vehicle electrical system, also be regarded as advantageous embodiments of the vehicle electrical system.

Description of the drawing:

In the following, an exemplary embodiment of the invention with reference to the accompanying drawings is explained in more detail. The single figure in a schematic circuit topology shows a vehicle electrical system with a vehicle electrical system voltage converter according to an embodiment of the invention.

The vehicle electrical system BN , For example, a hybrid electric vehicle includes a first electrical system branch BZ1 with a first vehicle electrical system voltage U1 , a second electrical system branch BZ2 with a second vehicle electrical system voltage U2 and a third electrical system branch BZ3 with a third vehicle electrical system voltage U3 ,

This is the first vehicle electrical system voltage U1 For example, 450 volts, the second board voltage U2 eg. 48 volts and the third vehicle electrical system voltage U3 eg 12 volts.

The electrical system BN further includes a voltage converter SW , which has a first and a second power connection A1 . A2 with the first electrical system branch BZ1 , via a third and a fourth power connection A3 . A4 with the second electrical system branch BZ2 as well as a fifth and fourth power connection A5 . A4 with the third electrical system branch BZ3 electrically connected.

The voltage converter SW is set up, the first vehicle electrical system voltage U1 in the second and the third board voltage U2 . U3 convert.

The voltage converter SW includes on the one with the first electrical system branch BZ1 electrically connected primary side PS a first and a second primary winding circuit WP1 . WP2 which is between the first and the second power connection A1 . A2 connected in parallel with each other electrically.

The two primary winding circuits WP1 . WP2 are substantially analogous to each other and each comprise a full bridge circuit VB1 . VB2 , Each of the two full bridge circuits VB1 . VB2 again comprises two identical half bridges HB1 . HB2 ; HB3 . HB4 , each a primary winding LP1 ; LP2 and one capacitor each KD1 ; KD 2 , Here are the primary winding LP1 . LP2 and the capacitor KD1 . KD 2 the respective full bridge circuits VB1 . VB2 between the respective two half-bridges HB1 . HB2 or. HB3 . HB4 connected in series. The half bridges HB1 . HB2 . HB3 . HB4 each include a positive voltage side HS11 . HS21 . HS31 . HS41 and a negative voltage side HS12 . HS22 . HS32 . HS42 Semiconductor switches, which are connected in series. The capacitors KD1 . KD 2 serve to reduce the DC components in currents flowing through the respective full bridge circuits VB1 . VB2 flow.

The voltage converter SW further comprises a control unit SE , Which signal output side with the control terminals of the positivspannungsseitigen HS11 . HS21 . HS31 . HS41 and a negative voltage side HS12 . HS22 . HS32 . HS42 Semiconductor switch is electrically connected and is set up to convert the first vehicle electrical system voltage U1 in the second and the third board voltage U2 . U3 the half bridges HB1 . HB2 . HB3 . HB4 or the semiconductor switch HS11 . HS21 . HS31 . HS41 ; HS12 . HS22 . HS32 . HS42 in a manner to be described below.

On one with the second and the third Bordnetzzweig BZ2 . BZ3 electrically connected, from the primary side PS galvanically isolated secondary side SS includes the voltage converter SW analogous to a first and a second secondary winding circuit WS1 . WS2 which is between the third and the fourth power connection A3 . A4 connected to each other serially.

The two secondary winding circuits WS1 . WS2 each comprise a secondary winding LS1 . LS2 and each one of the respective secondary windings LS1 . LS2 downstream rectifier GR1 . GR2 , Here are the secondary windings LS1 . LS2 the first and the second secondary winding circuits WS1 . WS2 with the respective primary windings LP1 . LP2 the first and the second primary winding circuits WP1 . WP2 Coupled electromagnetically in pairs.

The rectifier GR1 . GR2 each comprise two diodes D11 . D12 ; D21 . D22 , which with their collector terminals of the corresponding secondary winding LS1 . LS2 point. Alternatively, the two rectifiers GR1 . GR2 instead of the diodes D11 . D12 ; D21 . D22 Semiconductor switches, such as. B. metal oxide semiconductor field effect transistors (MOSFET), which then for the voltage conversion of the control unit SE in a manner known to those skilled synchronous with the semiconductor switches HS11 . HS21 . HS31 . HS41 ; HS12 . HS22 . HS32 . HS42 the half bridges HB1 . HB2 . HB3 . HB4 the two primary winding circuits WP1 . WP2 be controlled. Are the two rectifiers GR1 . GR2 equipped with semiconductor switches, so the voltage converter SW can also be operated bidirectional and the first vehicle electrical system voltage U1 in the second and the third board voltages U2 . U3 or the second and the third vehicle electrical system voltages U2 . U3 in the first electrical system voltage U1 convert.

The voltage converter SW further includes a smoothing choke LG between the two secondary winding circuits WS1 . WS2 is electrically connected and is set up, AC components in the second and the third from the first vehicle electrical system voltage U1 converted vehicle electrical system voltage U2 . U3 to reduce.

The voltage converter SW further includes a current path SP between the smoothing choke LG and the fifth port A5 and a controllable semiconductor switch ST in the current path SP. The semiconductor switch ST is set up, in an open switching state, the fifth connection A5 from the third port A3 to disconnect electrically. In a closed switching state, the semiconductor switch connects ST the second secondary winding circuit WS2 with the third electrical system branch BZ3 electric. In this case, the first rectifier GR1 inactive and serves with the two diodes D11 and D12 as a blocking element between the second and the third electrical system branch BZ2 . BZ3 ,

The voltage converter SW further comprises a control unit SE for controlling the semiconductor switch ST.

The voltage converter SW also includes another capacitor C1 between the first and the second connection A1 . A2 , another capacitor C2 between the third and the fourth connection A3 . A4 , as well as another capacitor C3 between the fifth and fourth connection A5 . A4 , These capacitors C1 . C2 . C3 serve to reduce voltage fluctuations in the first, the second and the third vehicle electrical system voltage U1 . U2 . U3 ,

After the circuit topology of the vehicle electrical system BN has been described in detail with reference to the figure, its operation will be described in more detail below.

For generating the second vehicle electrical system voltage U2 of 48 volts from the first vehicle electrical system voltage U1 of 450 volts controls the control unit SE the semiconductor switches HS11 . HS21 . HS31 . HS41 . HS12 . HS22 . HS32 . HS42 the half bridges HB1 . HB2 . HB3 . HB4 by means of pulse width modulated control signals offset from each other in time such that the two full bridge circuits VB1 . VB2 per signal period of the control signals offset from each other by 90 ° at the first vehicle electrical system voltage U1 be connected. The semiconductor switches HS11 . HS21 . HS31 . HS41 . HS12 . HS22 . HS32 . HS42 are controlled in such a way that the two full bridge circuits VB1 . VB2 once per period positively and once negatively at the first vehicle electrical system voltage U1 be connected.

The electromagnetic couplings and the corresponding adjustment of the duty cycle of the control signals occur at the two secondary winding circuits WS1 . WS2 each generate an output voltage of 24 volts. By the series connection of the two secondary winding circuits WS1 . WS2 occurs between the third and the fourth power connection A3 . A4 an entire output voltage of 48 volts, which then as the second board voltage U2 the second electrical system branch BZ2 provided.

For generating the third vehicle electrical system voltage U3 of 12 volts from the first vehicle electrical system voltage U1 of 450 volts, the control unit SE switches the semiconductor switches HS11 . HS12 . HS21 . HS22 the two half bridges HB1 . HB2 the first full bridge circuit VB1 and thus the first primary winding circuits WP1 consistently out. Furthermore, the control unit SE switches one of the two semiconductor switches HS41 one of the two half-bridges HB4 continuously on and the other semiconductor switch HS41 the same half-bridge HB4 continuously and thus drives the second full bridge circuit VB2 in a half-bridge operation mode.

This results in the output of the second secondary winding circuit WS2 at an unchanged duty cycle, an output voltage of 12 volts, that is half of a voltage of 24 volts that can be generated in a full bridge operating mode.

By turning off the first primary winding circuits WP1 arises in the first secondary winding circuit WS1 an output voltage of 0 volts.

The control unit SE further turns on the switch ST and thus connects the second secondary winding circuit WS2 with the fifth power connection A5 , This creates between the fifth and the fourth power connection A4 . A5 an output voltage of 12 volts, which then as the third board supply voltage U3 the third electrical system branch BZ3 provided.

By the corresponding adjustment of the switching frequency, the duty cycle and the switching times of the positive voltage side and the negative voltage side semiconductor switch HS11 . HS12 . HS21 . HS22 . HS31 . HS32 . HS41 and HS42 the two full bridge circuits VB1 . VB2 For example, zero current operation can be achieved in a half-bridge operating mode on the primary side PS, and consequently so-called reverse-recovery losses can be reduced on the secondary side SS.

Claims (9)

Vehicle electrical system voltage converter (SW) for converting a first vehicle electrical system voltage (U1) into a second vehicle electrical system voltage (U2) and a third vehicle electrical system voltage (U3), comprising: - A first power connector (A1) and a second power connector (A2) for connection to the first vehicle electrical system voltage (U1); two primary winding circuits (WP1, WP2) connected in parallel to each other between the first (A1) and second (A2) power terminals; a third power connection (A3) and a fourth power connection (A4) for providing the second vehicle electrical system voltage (U2); two secondary winding circuits (WS1, WS2) serially connected between the third (A3) and fourth (A4) power terminals; a fifth power terminal (A5) between the two secondary winding circuits (WS1, WS2) for providing the third vehicle electrical system voltage (U3) between the fifth (A5) and fourth (A4) power terminals; - Wherein one of the two primary winding circuits (WP1, WP2) and one of the two secondary winding circuits (WS1, WS2) are coupled in pairs with each other electromagnetically; a common smoothing choke (LG), which is electrically connected between the two secondary winding circuits (WS1, WS2) and is arranged to reduce AC components in the second (U2) and the third (U3) vehicle electrical system voltage, a controllable switch (ST) electrically connected between the smoothing choke (LG) and the fifth power terminal (A5) and arranged to electrically disconnect the fifth power terminal (A5) from the third power terminal (A3) in an open switching state. Vehicle electrical system voltage transformer (SW) to Claim 1 wherein the two primary winding circuits (WP1, WP2) each have a full bridge circuit (VB1; VB2) each having two half bridges (HB1, HB2; HB3, HB4) and one primary winding (LP1; LP2) between the two half bridges (HB1, HB2; HB3 , HB4). Vehicle electrical system voltage transformer (SW) to Claim 1 or 2 wherein the two secondary winding circuits (WS1, WS2) each comprise a secondary winding (LS1; LS2) and a respective rectifier (GR1; GR2) connected downstream of the respective secondary winding (LS1; LS2), the secondary windings (LS1, LS2) being connected to the respective primary windings (LP1, LP2) of the corresponding primary winding circuits (WP1, WP2) are electromagnetically coupled. Vehicle electrical system voltage converter (SW) according to one of the preceding claims, wherein the second vehicle electrical system voltage (U2) is above 40 volts, esp. At 48 volts. Vehicle electrical system voltage converter (SW) according to one of the preceding claims, wherein the third vehicle electrical system voltage (U3) is less than 40 volts, esp. At 12 volts. Vehicle electrical system voltage converter (SW) according to one of the preceding claims, wherein the two primary winding circuits (WP1, WP2) are formed identical to each other circuit technology, and / or the two secondary winding circuits (WS1, WS2) are formed identical to each other circuit technology. Vehicle electrical system voltage converter (SW) according to one of the preceding claims, further comprising a control unit (SE) for controlling the two primary winding circuits (WP1, WP2), which is adapted to the two primary winding circuits (WP1, WP2) offset from each other by 90 °. Vehicle electrical system voltage converter (SW) according to one of Claims 2 to 7 wherein the control unit (SE) is further arranged to turn off the full bridge circuit (VB1) of one of the two primary winding circuits (WP1) and to provide the full bridge circuit (VB2) of another of the two to provide the third onboard supply voltage (U3) Primary winding circuits (WP2) operate in a half-bridge operating mode. Vehicle electrical system (BN), comprising: - A first electrical system branch (BZ1) with the first vehicle electrical system voltage (U1); - A second electrical system branch (BZ2) with the second vehicle electrical system voltage (U2); - A third electrical system branch (BZ3) with the third vehicle electrical system voltage (U3); - A vehicle electrical system voltage converter (SW) according to one of the preceding claims, the first (A1) and the second (A2) power connector (A) with the first board network branch (BZ1), the third (A3) and the fourth (A4 ) Is electrically connected to the second electrical system branch (BZ2), and via the fifth (A5) and the fourth (A4) power connection to the third electrical system branch (BZ3) and is set up, the first vehicle electrical system voltage (U1) in the second vehicle electrical system voltage (U2 ) and the third vehicle electrical system voltage (U3).

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